微型pH电极的制备及其在牙菌斑pH检测中的应用

目的研制可用于牙菌斑pH原位检测的化学修饰性微型pH电极。方法采用氧化铱为氢离子敏感膜,以极化电解的方式将敏感膜附着于铂丝上,制备铂-氧化铱化学修改性微型pH电极,筛选性能优良的电极用于菌斑pH的原位检测,并与蜂式微型pH电极的检测进行对比。结果自制电极在pH值为1~11范围内呈线性响应,斜率为55.8mV/pH,响应时间为15~20s,电极在8h内的漂移为0.5~1.0mV,使用寿命大于1年。在对牙菌斑pH的原位检测中,自制电极与蜂式pH电极在漱糖后1h内各时间点测得的菌斑pH值差异均无显著性(P>0.05)。结论自制的铂-氧化铱化学修饰性微型pH电极对H+选择性好、性能稳定、响应范围广、响应时间短,在牙菌斑pH的原位检测中显示了良好的可行性。

Preparation of pH microelectrode and its application in plaque pH measurement

Objective To develop a chemically modified pH microelectrode which can be used in the measurement of dental plaque pH in situ. Methods Iridium oxide (IrO2) was used as the H+ sensitive membrane and attached to the surface of platinum wires by electroplating. Then,the pH responses of the microelectrodes were tested and the better ones were chosen for the measurement of the change of dental plaque pH within 1h after sucrose rinsing. The plaque of the symmetrical site was measured by the Beetrode pH microelectrode as a contrast. Results The homemade microelectrodes showed a linear response in the pH ranging from 1 to 11with response sensitivity of 55.8 mV/pH. The response time was about 15～20 s and potential drift was 0.5～1.0 mV/pH within 8h. Its life-span could be maintained at least 1 year. In the measurement of plaque pH,there were no statistical differences between the homemade and the Beetrode microelectrode. Conclusion The homemade IrO_2 microelectrodes show very promising pH sensing performance. They are considered to be feasible in the in situ measurement of plaque pH because of the good stability over a wide pH range,rapid response and being tiny enough to be inserted into the interproximal site of the teeth.